Abstract: To understand the effect of feedstock change on hydrotreated lube base oil, the physicochemical properties of vacuum gas oil (VGO), hydrocracking tail oil and hydrotreated base oil were analyzed to investigate the key factors that determine the viscosity-temperature performance of base oil. The results showed that the viscosity index(VI) and the sum of the mass fraction of paraffins, monocyclic naphthene and alkyl benzenes of VGO are positively correlated with the VI of base oil produced from VGO. The relations between VI and chemical compositions of the base oil indicated that the VI of the base oil was mainly affected by the content of paraffins and monocyclic naphthene, the distribution of carbon number and the degree of isomerization.

Key words: lube base oil, paraffin, naphthene, viscosity index